Lamp receptacle



arch 24, 1942. w. E. PARISH 2,277,348 LAMP RECEPTACLE Filed Feb. 19,1940 Patented Mar. 24, 1942 UNITED stares Grouse-Hinds Compan porationof. New York y, Syracuse, N. Y., a cor- Application February 19, 1940,Serial No. 319,708

3 Claims.

This invention relates to receptacles for the conventional electriclamp, or more particularly to the screw shell portion of suchreceptacles.

The invention has as an object a receptacle screw shell embodying astructure particularly economical to manufacture and which operates toyieldingly retain the base of the lamp in proper position in the screwshell under all conditions of vibration.

The invention consists in the novel features and in the combinations andconstructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanyingdrawing in which like characters designate corresponding parts in allthe views.

Figure 1 is a side elevational view of a lamp receptacle screw shellembodying my invention.

Figure 2 is a top plan view of the screw shell.

Figure 3 is a View taken on substantially line 3-3, Figure 1.

Figure 4 is an enlarged fragmentary view illustrating the action betweenthe threaded base of the lamp and the screw shell.

The general object of the invention is the provision of means to preventthe lamp from becoming loosened or unscrewing out of the screw shellunder conditions of excessive vibration. Heretofore, many constructionshave been suggested to obtain this result. In receptacles of this type,Q

it is customary to arrange one or more spring members within the screwshell and which function to yieldingly press against the lamp base inorder to retain it in the screw shell. This, and other structures toaccomplish the result, adds materially to the cost of manufacturing thescrew shell, and such structures are not entirely satisfactory.

The screw shell herein described is of cast metallic formation beingformed with a radially extending flange I adjacent the open end of theshell, and with an inwardly extending arcuate flange II to which a diskI2 of insulating material is secured as by screws l3 extending throughthe disk and threading into apertures formed in the flange II. Theparticular screw shell illustrated is intended for use in fittings suchas disclosed in Patent No. 2,174,773.

One side of the shell, adjacent the base thereof, is cut away to providean aperture I4 of appreciable dimensions. The center contact I5 issecured to the under side of the disk I2 and extends over the peripheraledge thereof and inwardly to engage the center contact of the lamp basein the conventional manner.

The contact I5 is secured to the disk I2 as by screw I I, and the wireI8 is connected to the contact by being secured under a binding nut I9threaded upon the screw. The opposite lead wire 20 is secured to theshell of the receptacle by screw ZI and nut 22.

The screw shell is formed with an internal thread 23 which is in formcomplemental to the thread on the base of the lamp, being however of adifferent pitch than the thread on the lamp base. Preferably the thread23 is of lesser pitch than the thread on the lamp base. For example, thethread on the conventional medium lamp base is seven, while the pitch ofthe thread 23 is six and three-quarters. Accordingly, as the lamp baseis threaded into the screw shell, the threads of the two members tend tobind because of the difference in pitch, and when the base is threadedinto the screw shell a sufficient distance to effect proper contactbetween the central contact of the lamp and the contact l5, this bindingeffect is appreciable and I have found that the lamp will not loosen orunscrew out of the screw shell under any condition of vibration.

It will of course be understood that conventional electric lamps aremanufactured and sold with five different sizes of bases known asMiniature having 14 pitch thread, Candelabra having 10 pitch thread,Intermediate having 9 pitch thread, Medium having 7 pitch thread, andMogul having a 4 pitch thread. Accordingly, a screw shell comparable toany one of the conventional lamp bases will be formed with its thread ofslightly different pitch than the pitch of the thread on the particularlamp base.

In order that there may be some resiliency in the screw shell to preventexcessive binding between the lamp base and the shell, particularly inconnection with a heavy cast metallic screw shell, I form the screwshell with a plurality of slots extending inwardly from the open end ofthe shell toward the base thereof. There are four such slots shown inthe accompanying drawing, the slots of each pair being arranged inalinement. The slots 25 are diametrically opposed, one of the slotsbeing arranged centrally of the aperture I l. The second pair of slots26 are arranged in opposite sides of the screw shell but spaced to oneside of the center thereof, the arrangement being such that the slots 26are arranged remote from the side portion of the screw shell in whichthe aperture 14 i formed. This specific arrangement is to effectsubstantially the same resiliency to each section of the shell, the

length of the sections varying because of the aperture l4.

What I claim is:

1. A metallic lamp receptacle screw shell formed with an internal threadto receive a threaded base of a conventional electric lamp, saidinternal thread being of different pitch than the thread on the lampbase, and said screw shell being non-yielding in axial direction andbeing formed with a plurality of radially yieldable sections.

2. A metallic lamp receptacle screw shell provided with an internalthread to receive the threaded base of a conventional electric lamp,said internal thread being of different pitch than the thread on thelamp base, said screw shell being non-yielding in axial direction andbeing formed with a plurality of slots extending from the open end ofsaid shell toward the base thereof and forming radially yieldablesections.

3. A metallic lamp receptacle screw shell formed with an opening in oneside adjacent the base thereof, diametrically opposed slots extendinginwardly from the open end of said shell toward the base thereof, one ofsaid slots extending into said opening, a second pair of opposed slotsarranged in angular relationship to said first mentioned slots andremote from said aperture, said slots forming radially yieldablesections, said screw shell being provided with an internal thread toreceive the threaded base of a conventional electric lamp, and saidinternal threads being of lesser pitch than the thread on the lamp base.

WILLARD E. PARISH.

